Spectroscopic and Spectropolarimetric Observations of V838 Mon

Abstract

The spectroscopic and spectropolarimetric variability of the peculiar variable V838 Monocerotis during the brighter phases of its multiple outbursts in 2002 is presented. Significant line profile variability of H$α$ and Si II 6347.10Å& 6371.36Åoccurred in spectra obtained between 2002 February 5 and 2002 March 14, and a unique secondary absorption component was observed near the end of this time period. Our observations also suggest that multiple shifts in ionization states occurred during the outbursts. Spectropolarimetric observations reveal that V838 Mon exhibited both intrinsic and interstellar polarization components during the initial stages of the second outburst, indicating the presence of an asymmetric geometry; however, the intrinsic component had significantly declined by February 14. We determine the interstellar polarization to be $P_{max} = 2.746 \pm 0.011 %$, $λ_{max} = 5790 \pm 37Å$, $PA = 153.43 \pm 0.12 ^{\circ} $, and we find the integrated intrinsic V band polarization on February 5 to be $P = 0.983 \pm 0.012 %$ at a position angle of $127.0 \pm 0.5^{\circ}$. The implications of these observations for the nature of V838 Monocerotis, its distance, and its ejecta are discussed.